1. Field of the Invention
The general field of the invention relates to unique electromagnetic components having electrical characteristics that are variable. The components can be used for radiating and non-radiating electromagnetic devices. Embodiments of the invention also relate to electrical devices having elements structured on LCD, such that the operation of the LCD changes the characteristics of the electrical devices.
2. Related Arts
Various electrical devices/components are known in the art for receiving, transmitting, and manipulating electrical signals and electro-magnetic radiation. The feed or transmission lines or network conveys the signal between the radiating antenna and the transceiver. However, the feed network may comprise different type of transmission lines, bends, power splitters, filters, ports, phase shifters, frequency shifters, attenuators, couplers, capacitors, inductors, diplexers, hybrids of beam forming networks, and may also include radiating elements. Similar arrangement may be in transmission lines which do not transmit wirelessly, e.g., coaxial transmission of television programming. These elements may be static or variable. For example, a capacitor may have a given, i.e., static capacity, or it may be variable, e.g., by mechanically changing the distance between the capacitor plates. Other devices, such as transmission lines, for example, are static in that their electrical characteristics (such as resistance or impedance) do not change.
While the devices disclosed herein are generic and may be applicable to multitude of applications, one particular application that can immensely benefit from the subject devices are the transmission of signals in mobile devices which operate in several frequencies. In such devices, an elaborate network of switches and filters are used to couple one of several transceivers to the antenna. Such network increases the cost of the devices and leads to losses which attenuate the signal, thus requiring increasing the power of the transmitter to thereby consume more battery power.
There are several types of microstrip antennas (also known as a printed antennas), the most common of which is the microstrip patch antenna or simply patch antenna. A patch antenna is a narrowband, wide-beam antenna fabricated by etching the antenna element pattern in metal trace bonded to an insulating substrate. Some patch antennas eschew a substrate and suspend a metal patch in air above a ground plane using dielectric spacers; the resulting structure is less robust but provides better bandwidth. Because such antennas have a very low profile, are mechanically rugged and can be conformable, they are often mounted on the exterior of aircraft and spacecraft, or are incorporated into mobile radio communications devices.
An advantage inherent to patch antennas is the ability to have polarization diversity. Patch antennas can easily be designed to have Vertical, Horizontal, Right Hand Circular (RHCP) or Left Hand Circular (LHCP) Polarizations, using multiple feed points, or a single feedpoint with asymmetric patch structures. This unique property allows patch antennas to be used in many types of communications links that may have varied requirements.
FIG. 1 illustrates an example of a microstrip antenna of the prior art. As shown in FIG. 1, four conductive patches 105-120 are provided over insulating substrate 130. A base “common” ground conductor is provided below the dielectric 130, but is not shown in FIG. 1. Conductive lines 105′-120′ provide electrical connection to main line 140, which is connected to a central feed line 145.
A liquid crystal display (commonly abbreviated LCD) is a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source or reflector. Each pixel of an LCD consists of a layer of perpendicular molecules aligned between two transparent electrodes, and two polarizing filters, the axes of polarity of which are perpendicular to each other. The liquid crystal material is treated so as to align the liquid crystal molecules in a particular direction. This treatment typically consists of a thin polymer layer that is unidirectionally rubbed using a cloth (the direction of the liquid crystal alignment is defined by the direction of rubbing).
Before applying an electric field, the orientation of the liquid crystal molecules is determined by the alignment at the surfaces. In a twisted nematic device (the most common liquid crystal device), the surface alignment directions at the two electrodes are perpendicular, and so the molecules arrange themselves in a helical structure, or twist. Because the liquid crystal material is birefringent, light passing through one polarizing filter is rotated by the liquid crystal helix as it passes through the liquid crystal layer, allowing it to pass through the second polarized filter. Half of the light is absorbed by the first polarizing filter, but otherwise the entire assembly is transparent.
When a voltage is applied across the electrodes, a torque acts to align the liquid crystal molecules parallel to the electric field, distorting the helical structure (this is resisted by elastic forces since the molecules are constrained at the surfaces). This reduces the rotation of the polarization of the incident light, and the device appears darker. If the applied voltage is large enough, the liquid crystal molecules are completely untwisted and the polarization of the incident light is not rotated at all as it passes through the liquid crystal layer. This light will then be polarized perpendicular to the second filter, and thus be completely blocked and the pixel will appear black. By controlling the voltage applied across the liquid crystal layer in each pixel, light can be allowed to pass through in varying amounts, correspondingly illuminating the pixel.
FIG. 2 illustrates a cross-section of an LCD of the prior art. As shown in FIG. 2, the LCD 200 comprises a back panel 205 which may be glass, a front panel 210 which is also generally made of glass, a liquid crystal 215 positioned between the two panels, a back electrode 220 (corresponding to the common ground conductor of FIG. 1), which may be indium/titanium/oxide (ITO), aluminum, etc, and front electrodes 225, which are coupled to potential 230 and are generally made of ITO. The potential 230 may be applied individually to each electrode 225. As potential is applied to an electrode 225, the liquid crystal below it changes its orientation and, thereby changes the local dielectric constant between the powered electrode and the section of the rear electrode corresponding to the area of the front electrode.